There are a ton of crooks on evilbay. There was a guy arrested a few month back, he stole a lot sum of money by selling computers. At first he was sending them out to customers, but then he decided to keep 100% profit. He even paid people $50 for leaving him possitive feedback before receiving the goods.
Also be careful if you receive 'ebay' e-mails asking for you to login. Ebay will never e-mail you anything like that. I have gotten a few e-mails like that before, they look very real to a person who never suspectes anything.